1. Technical Field
The present invention relates to an apparatus and method for extending a bandwidth of a sound signal.
2. Description of the Related Art
Recently, Internet-based phone services have entered widespread use. Widespread use of Internet-based phone services results from realization of communication based on a super wideband of 50-14000 Hz and providing higher quality than existing communication networks. Codecs, which support super wideband communication, include G.729.1SWB (super wideband) proposed by ITU-T, and the like.
Codecs, which support super wideband communication, have a feature of embedded variable bitrates. Therefore, the codec encodes information at a lower bitrate, when the number of users increases, communication congestion occurs, and the like. Here, low bitrate information is a narrowband signal and thus only information about low band sound carrying a lot of voice information is transmitted. Accordingly, it is advantageously possible to prevent sharp deterioration in call quality due to packet loss, to improve service connectivity, and to permit communication and interaction between heterogeneous terminals having different communication abilities.
However, if transmission is performed at a low bitrate, there can be user inconvenience due to recognizable deterioration in call quality, even though it is possible to prevent sharp deterioration in call quality. Such a problem is more serious when service quality is sharply degraded due to sudden deterioration of a communication network. In particular, such a problem occurs more frequently and becomes further serious when a user terminal connected to a wireless Internet protocol network moves.